This invention generally relates to a method of controlling a change in a torque value of a semi-automated vehicle transmission system that oscillates a torque value about a target torque value.
Vehicle transmissions are well known and include automatic, manual and semi-automatic types. Each of the transmission types have advantages that make them suitable for various applications. Heavy duty vehicles typically include a manual or, more recently, a semi-automatic transmission. Semi-automatic transmissions of various types have been proposed. The basic principal is to assist a driver in performing a manually selected gear ratio change using a system that is at least partially automated. While such transmissions are becoming more readily useable, those skilled in the art are still trying to enhance and perfect current designs.
In conventional manual transmissions, to effect a gear change, the driver of the vehicle would manually operate a clutch and a gear shift lever. The clutch was used to disengage the output shaft of the engine from the input shaft of the transmission so that the driver would be able to move the transmission out of a current gear into a neutral position. To then re-engage a new gear, the driver would have to operate the clutch, move the lever and approximate a desired engine speed that would correspond to an appropriate torque for engaging the new gear. Traditionally, this has been a relatively difficult maneuver requiring a great degree of skill and experience.
One challenge facing a designer of a semi-automatic transmission system is to simplify the task of shifting gears and doing so in an efficient and effective manner. This invention provides an effective method for establishing conditions that simplify effecting a gear change in an efficient manner.